The world needs a new source of energy, an unspillable source.

How do they get wind powered electricity to city/power grid?

I am curious of how they get the electricity produced by a windmill or even solar panel to a city or a city’s power grid or city’s electric plant. I know obviously they have to send it via wires underground but does anyone have more info on the process like installation, how the electric system (how they send electricity to a grid with out over loading it.